Cotter climate

Cotter Frost Dates and Growing Season

NOAA 1991-2020 normals for Mtn Home 1 Nnw, 15.1 km from Cotter, elevation 800 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Mtn Home 1 Nnw. A median date has an even chance of a later freeze in spring, or an earlier one in fall.

The last spring freeze typically comes around March 31 and the first fall freeze around November 1, a growing season of about 214 days.

Median at 36°F
last April 12, first October 23
Median at 32°F
last March 31, first November 1
Median at 28°F
last March 20, first November 12

Last freeze in spring

The chance of a later freeze than the date shown. At 10 percent, one spring in ten still freezes after the date; planting after the 10 percent date for 32°F is the cautious choice.

Threshold10%20%30%40%50%60%70%80%90%
36°FApr 30Apr 26Apr 21Apr 15Apr 12Apr 9Apr 5Apr 2Mar 27
32°FApr 18Apr 10Apr 7Apr 4Mar 31Mar 29Mar 25Mar 20Mar 14
28°FApr 5Mar 31Mar 28Mar 24Mar 20Mar 17Mar 13Mar 8Mar 3
24°FMar 28Mar 22Mar 17Mar 13Mar 10Mar 6Mar 3Feb 27Feb 21
20°FMar 17Mar 12Mar 8Mar 4Feb 28Feb 24Feb 19Feb 14Feb 5
16°FMar 10Mar 4Feb 28Feb 22Feb 17Feb 11Feb 6Jan 31Jan 22

First freeze in fall

The chance of an earlier freeze than the date shown. At 10 percent, one fall in ten freezes before the date.

Threshold10%20%30%40%50%60%70%80%90%
36°FOct 11Oct 15Oct 18Oct 21Oct 23Oct 25Oct 28Oct 31Nov 4
32°FOct 19Oct 23Oct 27Oct 30Nov 1Nov 3Nov 7Nov 11Nov 17
28°FOct 30Nov 2Nov 5Nov 8Nov 12Nov 15Nov 19Nov 25Dec 1
24°FNov 5Nov 10Nov 14Nov 19Nov 23Nov 27Dec 1Dec 6Dec 14
20°FNov 14Nov 20Nov 26Dec 1Dec 5Dec 10Dec 15Dec 22Dec 29
16°FNov 24Dec 1Dec 9Dec 15Dec 21Dec 26Dec 31Jan 5Jan 14

Growing season length

Days between the last spring and first fall freeze at each threshold, with the chance of a season at least that long.

Threshold10%20%30%40%50%60%70%80%90%
36°F213207201196193188183178170
32°F238229223218214210206200191
28°F261253247242237231225220213
24°F284277271264259253249242233
20°F310301293286280274268261251
16°F335324317310304298291283270

How often it gets that cold

The share of years with at least one night at or below each temperature.

36°F or colder
100% of years
32°F or colder
100% of years
28°F or colder
100% of years
24°F or colder
100% of years
20°F or colder
100% of years
16°F or colder
99% of years

Degree days

A degree day is one degree of the daily mean temperature beyond a base, for one day. Heating degree days count cold (the fuel a house burns), cooling degree days heat, growing degree days the warmth a crop needs; each crop has its own base.

Heating degree days, base 65°F
3,989
Cooling degree days, base 65°F
1,550
Growing degree days, base 40°F
7,220
Growing degree days, base 45°F
5,793
Growing degree days, base 50°F
4,511
Growing degree days, base 55°F
3,374
Growing degree days, base 60°F
2,389

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January901015
February699128
March5177106
April23829271
May74112505
June4299745
July0437902
August1413877
September28203626
October21145320
November509495
December809022

What this means

NOAA computes these from the daily lows at the station over 1991-2020, fitting the dates of each year's last and first freeze to a distribution, so a date can be stated at any level of risk. 36°F is a frost risk for tender plants on a clear, calm night, since the ground cools below the air above it; 32°F is a freeze; 28°F is a hard freeze that kills most annuals.

The station is 15.1 km from Cotter. Low ground, valleys and open fields freeze earlier and later than a town center or a hillside.

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Sources

NOAA NCEI U.S. Climate Normals, 1991-2020, annual and seasonal normals for station USC00035036 (Mtn Home 1 Nnw). Public domain.